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Question

How many flight planning programs are available worldwide?

Answer

ICAO provides telephony designators to aircraft operators worldwide. These consist of the three letter airline identifer and a one or two word designator. They are usually, but not always, similar to the aircraft operator name. Thus the identifer for Aer Lingus is EIN and the designator is Shamrock while Japan Airlines International is JAL and Japan Air . So a flight by Aer Lingus numbered 111 would be written as "EIN111" and pronounced "Shamrock One-One-One" on the radio, while a similarly numbered Japan Airlines flight would be written as "JAL111" and "Japan Air One-One-One".

— Source: Wikipedia (www.wikipedia.org)